The prosecution introduce this death into the trial as an incident giving Peterson the idea of how to fake Kathleens accident. During the trial,The Staircase Season 1 DVD Petersons daughters stand steadfastly by their father. The prosecution argues that Kathleen had discovered that Michael was bisexual and had been having affairs with men,The StaircaseSeason 1 which led to an argument in which he bludgeoned her to death. Peterson claimed that his wife knew about his sexuality and that they had an open marriage.